So-called peristaltic pumps involve the use of a roller applying pressure along the length of a flexible tube and forcing the liquid through the tubing. Because the peristaltic pump removes all of the liquid from the section of flexible tube which is being engaged by the moving roller, such pumps are well suited for pumping measured amounts of liquid in a sterile environment. Up until recently, these pumps had been used principally for filling Petri dishes with agar, by way of specific example. The size of the flexible tubing which is provided for use with commercial peristaltic pumps is characteristically in the order of one-quarter inch outer diameter, and the tubes are approximately two feet in length, although the part of the tube which is actively engaged by the pressure roller is less than one foot in length.
When it is desired to use a peristaltic pump for transfer of intravenous (IV) liquids, with the greatly increased requirement for absolute sterility, it has been the practice to use a sterile package of the two-foot long, one-quarter inch outer diameter silicone rubber tubing, and an available secondary transfer set, and to assemble them by hand. The secondary transfer set includes a fitting for securing to one end of the silicone rubber tubing, a roller valve on the small diameter plastic tubing, and a large vented spike for attaching to a large container of diluent. A vented needle is secured to the other end of the silicone rubber tubing for supplying the pumped intravenous liquid to a manufacturer's "Piggy-Back" vials or bottles (often referred to as "I.V.P.B.'s") containing powder to be reconstituted.
The rubber tubing for use in the peristaltic pump and the secondary transfer set should be assembled in sterile laminar flow hood conditions, but this procedure is time-consuming and often dispensed with, at the risk of touch contamination where the parts are joined. In addition, the female connector end of the silicone rubber tubing can split if undue pressure is applied, leaving a space for leakage of the fluids being transferred and for possible contamination. Also, when the quarter-inch diameter silicone rubber tube extends to the outlet of the system, there is some tendency for liquid to flow, even after shut-off of the valve. One type of diluent which is frequently used is a five percent dextrose solution, and such solutions constitute an ideal breeding point for bacteria. The slow rate of transfer of fluid is also inconvenient, as the prior transfer units required approximately 18 seconds for filling each standard size 100 milliliter bottle, with 50 cc of diluent, and a large number of bottles must often be filled. Further, when attempts have been made to increase the flow rate by doubling the number of rollers engaging the tube, it was found that the peristaltic motors would burn out in view of the additional load.
Accordingly, a principal object of the present invention is to provide a simple unitary fluid transfer unit for peristaltic pumps which avoids the problems of slow speed and lack of sterility which have been present in the makeshift arrangements previously utilized.